This invention relates to electronic control systems for static power converters and is applicable to any converter of this kind. One single control system can govern a number of similar power converters in such a manner that operation of the power converters are staggered in time. For instance, two so-called "choppers" can operate in a sequence so that the pulses of the second chopper appear in time between the pulses of the first chopper; yet, the sum of the pulses of both choppers is fed into one single output. This sequence of pulses is so governed by one single control system that it will perform a function as if these pulses were emanating from one single source i.e., from one single chopper.
The following prior art are introduced for the purpose of reference and are believed pertinent to the present invention.
U.S. Pat. No. 3,659,184 issued Apr. 25, 1972, Analog Signal to Discrete Time Interval Converter (ADCTIC), Francisc C. Schwarz; "An Improved Method of Resonant Current Pulse Modulation for Power Converters", Francisc C. Schwartz, IEEE Transactions on Industrial Electronics and Control Instrumentation, Vol. IECI-23, No. 2, May 1976; U.S. Pat. No. 3,953,779 issued Apr. 27, 1976, Electronic Control System for Efficient Transfer of Power through Resonant Circuits, Francisc C. Schwarz; U.S. Pat. No. 4,096,557 issued June 20, 1978, Controllable Four Quadrant A.C. to A.C. and D.C. Converter Employing an Internal High Frequency Series Resonant Link, Francisc C. Schwarz; U.S. Pat. No. 3,663,940 issued May 16, 1972, Controllable Load Insensitive Power Converters, Francisc C. Schwarz; "Principles of Inverter Circuits" by B. D. Bedford and R. G. Hoft, Wiley, 1964, New York.
The above explained philosophy is applicable to a number of power converters larger than two. It is then possible to attain a sequence of modulated pulses at a given frequency; yet, each of the pulse supplying mechanisms originates at a lower frequency, which is a fraction of the resulting total converter frequency.
In this way it is possible to obtain a sequence of pulses with a time resolution, that is an excess of the resolution that could be obtained with the components of one single converter.